The present invention relates to an iron type golf club head that is helpful to gain a large carry.
Conventionally, the orientation of a hit ball and the ease of lifting a ball has been thought more important than on the carry of a hit ball where an iron type golf club is concerned. However, in recent years, the technology for wood type golf clubs has improved, significantly increasing carry, and therefore, the difference in carry between iron type golf clubs and wood type golf clubs has been enlarged. As a result of this, recently, many golfers tend to place importance on the function also of iron type golf clubs in terms of carry.
In order to increase the function of golf clubs in terms of carry, it is considered to be effective to increase the coefficient of restitution of the head. The prior arts of Japanese published patent application No. 2001-129131, and No. 2001-29523 are examples, and describe that a dent or the like is provided on the back side of the face portion which hits a ball, so that a portion having a small thickness is provided.
However, there are many restrictions about a the head shape and the thickness of an iron type golf club head in comparison with a wood type golf club head, and it is not easy to increase the coefficient of restitution of an iron type golf club head.
An increase in the coefficient of restitution is a factor for increasing the initial speed of a hit ball, while the carry of the hit ball is not actually determined exclusively by the coefficient of restitution, but rather is significantly affected by the angle of the hit ball and the amount of backspin. In addition, the above described angle of the hit ball and the amount of backspin change depending on the point of the face where the ball is hit, thus, causing a variation in the carry.
Accordingly, it becomes important in order to gain a stable large carry, that a carry in the case where the hitting point of the face is shifted upward or downward from the sweet spot does not cause so different carry in comparison with the case where the hitting point is on the sweet spot of the face.